Saturday, June 3, 2017

Network Protocols
TCP has no special "I lost a packet!" message. Instead, ACKs are cleverly reused to indicate loss. Any out-of-order packet causes the receiver to re-ACK the last "good" packet – the last one in the correct order. In effect, the receiver is saying "I received packet 5, which I'm ACKing. I also received something after that, but I know it wasn't packet 6 because it didn't match the next sequence number in packet 5."

If two packets simply got switched in transit, this will result in a single extra ACK and everything will continue normally after the out-of-order packet is received. But if the packet was truly lost, unexpected packets will continue to arrive and the receiver will continue to send duplicate ACKs of the last good packet. This can result in hundreds of duplicate ACKs.

When the sender sees three duplicate ACKs in a row, it assumes that the following packet was lost and retransmits it. This is called TCP fast retransmit because it's faster than the older, timeout-based approach. It's interesting to note that the protocol itself doesn't have any explicit way to say "please retransmit this immediately!" Instead, multiple ACKs arising naturally from the protocol serve as the trigger.

Tuesday, May 16, 2017

MP3s as a litmus test for good journalism

The MP3 format was invented by a German group in the early 90s.  They patented it, and licensed it out to companies.  This is the reason many open source programs force you to download MP3 libraries separately.

The last patents for mp3 expire this year (2017).  Now anyone can use it without having to worry about licenses.  The group that created it announced they would stop licensing it (since they can't) and suggested people move to AAC (since they still own patents on that).

The result is news organizations running stories with headlines like "MP3 is Dead".  This presents and interesting look into which sources are reliable sources for tech news, and which use hyperbolic headlines for the sake of clicks. 

I went to Google News and searched for recent articles that mentioned 'MP3'.  Some of these were pretty obvious, but some were surprising.  To be fair, some are technically correct, in saying the creator declared it dead, vs saying it actually is dead, but merely parroting a press release is still going under the 'Bad' category.  The BBC was close, but I put it in good because it didn't feel clickbaity to me, feel free to disagree.

Finally, I won't pretend like this single example is some end all test for who you should and shouldn't trust, it's just and interesting source of some empirical data.


NPR: The MP3 Is Officially Dead, According To Its Creators
The Atlantic: The End of the MP3
Gizmodo: Developers of the MP3 Have Officially Killed It
The Register: MP3 'died' and nobody noticed
Quartz: Say goodbye to the iconic MP3
CNBC: The MP3 is dead, say creators after terminating licensing
The Telegraph: Creators of the MP3 declare it dead
Tech Radar: RIP MP3 - the sound file that changed the world is declared dead


Washington Post: Your MP3s are going to be just fine
Mashable: The MP3 isn't dead yet, but it's now on its last digital legs
Vice: The MP3 Is Not Dead
CNET: MP3 isn't dead, it's just sleeping
BBC: It might be time to say goodbye to the MP3 - so let's look back at its life

Friday, May 12, 2017

Are Pop Lyrics Getting More Repetitive?

This is some good data, but the presentation is very interesting as well.

Tuesday, April 25, 2017

Github has all the best cat stories
In broad daylight, we could see why this was street cat utopia. What used to be a deli or some other food store collapsed in what looks like the 80s. A tree had grown through the inside where the roof had collapsed, a branch somehow punching through brick wall and completely enveloping a piece of old metal shelving. There was no way into this place past the first few steps. The roof was collapsed with a capital C. You could see through the busted rafters towards the middle of the (what was now) one big room of the first floor, and to the street cats that were lazily napping in the sun, protected by their fortress.

Tuesday, March 14, 2017


I've been reading through these replies about "MediTech" trying to determine if it's some sort of elaborate inside joke I'm not picking up on.
There is a company called MediTech in Massachusetts that uses a derivative language of MUMPS called Magic. I know several programmers that have worked there. There are thousands of engineers writing in this language as we speak.
From what I can remember:

-Only global variables

-Variables must only be capital letters, maximum length 6. If you run out of variables, you must cleverly use them in a routine and set them back to what they are. This means you can't use a name like myVar - you use AAAFD, ZBVCXZ, etc.

-System functions are usually things like ., >, ', ], so code looks like .'AAAF]{\;:..

-Meditech writes all of their own languages, databases, operating systems, tools, etc. You can only write in a non-Meditech language if you get approval from a multi-tiered architectural design board, which barely ever happens

-The founder hated C with undying passion. No one is ever allowed to use C

-All programming hires go through a 6 to 12 month training process to learn the tools, languages, and systems. As they almost exclusively hire non-CS majors, such as math and physics majors, they don't typically have a programming background and don't realize how bizarre the MediTech stack is

Monday, March 6, 2017

A Good Overview of How Trump Operates

I try not to post a lot of political or topical stuff here, but this is a very good overview of Trump and how he operates.  It goes into a lot more background and detail than just the current Russia story.
Whenever he is under fire for something in a sustained way, he makes a shocking claim or provocative declaration about something else to change the subject. He is a master practitioner at the politics of distraction. These five examples might jog your memory:
  • After struggling during the first GOP primary debate to explain his disparaging comments about women, he attacked Megyn Kelly. “There was … blood coming out of her wherever,” he said, ensuring that the media focused on the new Trump-Kelly “feud.”
  • In November, the morning after agreeing to settle a fraud lawsuit against Trump University for $25 million, he demanded that the cast of “Hamilton” apologize to Mike Pence.
  • Perturbed when critics pointed out that he lost the popular vote, he claimed that 3 million to 5 million people voted illegally.

Saturday, February 11, 2017

Top mentioned books on

We analysed more than 40 000 000 questions and answers on to bring you the top of most mentioned books (5720 in total)

How we did it:
  • We got database dump of all user-contributed content on the Stack Exchange network (can be downloaded here)
  • Extracted questions and answers made on stackoverflow
  • Found all links and counted it
  • Created tag-based search for your convenience
  • Brought it to you

Saturday, January 28, 2017

Overjustification effect
The overjustification effect occurs when an expected external incentive such as money or prizes decreases a person's intrinsic motivation to perform a task. The overall effect of offering a reward for a previously unrewarded activity is a shift to extrinsic motivation and the undermining of pre-existing intrinsic motivation. Once rewards are no longer offered, interest in the activity is lost; prior intrinsic motivation does not return, and extrinsic rewards must be continuously offered as motivation to sustain the activity.

Sunday, January 15, 2017

The Line of Death
The Metro/Immersive/Modern mode of Internet Explorer in Windows 8 suffered from the same problem; because it was designed with a philosophy of “content over chrome”, there were no reliable trustworthy pixels. I begged for a persistent trustbadge to adorn the bottom-right of the screen (showing a security origin and a lock) but was overruled. One enterprising security tester in Windows made a visually-perfect spoofing site of Paypal, where even the user gestures that displayed the ephemeral browser UI were intercepted and fake indicators were shown. It was terrifying stuff, mitigated only by the hope that no one would use the new mode.